<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: Administrator
  Date: 2021/3/15 0015
  Time: 10:28
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<c:set var="username" value="sd"></c:set>
<c:if test="${empty pageScope.username}">
    <a href="">登录</a>
</c:if>
<c:if test="${not empty pageScope.username}">
 欢迎你，${pageScope.username}
</c:if>
</body>
</html>
